Human immunodeficiency virus type 1 infection of CD4+ T cells down-regulates the expression of CD28: effect on T cell activation and cytokine production.
ABSTRACT Infection with human immunodeficiency virus type 1 (HIV-1) results in dysregulation of normal T cell function. To study the effects of HIV-1 at the cellular level, primary T cell lines were generated by alloantigen stimulation of CD4+ T cells collected from peripheral blood of HIV-1-infected donors. Using Epstein-Barr virus-infected B lymphocytes (EBV-LCL) as a source of alloantigen, the T cell lines were expanded in vitro for 7 weeks. Uninfected T cell lines were cultured in parallel. Virus was inducible from the infected lines with stimulation, and complete infection was achieved after 4-7 weeks depending on the line. The down-modulation of CD28 expression correlated with virus replication and spread. Furthermore, CD28 mRNA was not inducible in the infected lines after stimulation with alloantigen. Loss of CD28 correlated with reduced responsiveness to costimulation with a monoclonal antibody to CD28 following similar engagement of the CD3 protein. In contrast, activation with alloantigen was not affected. HIV-1 infection and down-modulation of CD28 did not alter the relative levels of IL-2, IFN-gamma, and IL-4 mRNA. Production of the various cytokine mRNAs following alloantigen stimulation was inhibited by CTLA4Ig and thus remained under the regulation of CD80 and CD86 expressed on the EBV-LCL. Taken together, our data suggest that dysregulation of normal T cell function associated with HIV-1 infection may result in part form the loss of CD28 expression.
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ABSTRACT: It is well-known that HIV-1 infection results in a gradual decline of the CD4+ T-lymphocytes, but the underlying mechanism of this decline is not completely understood. Research has shown that HIV-1 infection of CD4+ T cells results in decreased CD28 expression, but the mechanism of this repression is unknown. There is also substantial evidence demonstrating regulatory involvement of microRNA (miRNA) during protein expression in plants and some animals, and reports have recently been published confirming the existence of viral-encoded miRNAs. Based on these findings, we hypothesize that viral-encoded miRNA from HIV-1 may directly alter T cell, macrophage and dendritic cell activity. To investigate a potential correlation between the genomic complementarity of HIV-1 and host cell protein expression, a local alignment search was performed to assess for regions of complementarity between the HIV-1 proviral genome and the mRNA coding sequence of various proteins expressed by CD+ T cells and macrophages. Regions of complementarity with strong correlations to the currently established criteria for miRNA:target mRNA activity were found between HIV-1 and CD28, CTLA-4 and some interleukins, suggesting that HIV-1 may produce translational repression in host cells.Journal of Theoretical Biology 08/2005; 235(2):169-84. DOI:10.1016/j.jtbi.2005.01.001 · 2.30 Impact Factor
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ABSTRACT: Although a number of studies on the phenotypic changes that occur after T-cell activation have already been published, the specific immunophenotypic features of T-lymphocytes and the frequency at which TCR-variable region (TCR-V) restricted T-cell expansions occur "in vivo" during acute viral infection still remains to be established. We report on the immunophenotype and TCR-V repertoire of peripheral blood T-cells from 28 patients with acute infectious mononucleosis. Immunophenotypic studies were performed by flow cytometry using direct immunofluorescence techniques and stain-and-then-lyse sample preparation protocols with three- and four-colour combinations of monoclonal antibodies directed against a large panel of T- and NK-cell associated markers, activation- and adhesion-related molecules and TCR-Vbeta, -Vgamma and -Vdelta families. Nearly all patients (27/28) showed a massive expansion of CD8(+)/TCRalphabeta(+) T cells, the majority (>90%) of which displayed an immunophenotype compatible with T-cell activation: CD2(+high), CD7(+low), CD11a(+high), CD38(+high), HLA-DR(+high), CD28(+/-low), CD45RO(+high), CD45RA(-/+low), CD11b(-/+low), CD11c(+/-low), CD16(-), CD56(-), CD57(-), CD62L(-), CD94(-), CD158a(-), CD161(-), NKB1(-). Additionally, the levels of both CD3 and CD5 were slightly decreased compared to those found in normal individuals. Late-activation antigens, such as CD57, were found in small proportions of CD8(+)/TCRalphabeta(+) T-cells. Increased numbers of CD4(+)/TCRalphabeta(+) T-cells, TCRgammadelta(+) T-cells and NK-cells were also noticed in 17, 16 and 13 of the 28 cases studied, respectively. Evidence for activation of CD4(+)/TCRalphabeta(+) and TCRgammadelta(+) T-cells relied on changes similar to those described for CD8(+)/TCRalphabeta(+) although less pronounced, except for higher levels of both CD5 and CD28 in the absence of reactivity for CD11c on CD4(+)/TCRalphabeta(+) T-cells and higher levels of CD161 and CD94 on TCRgammadelta(+) T-cells. Small expansions of one or more TCR-Vbeta families accounting for 12 +/- 7% of either the CD8(+)/TCRalphabeta(+) or the CD4(+)/TCRalphabeta(+) T-cell compartment were found in 12 of 14 patients studied, whereas the distribution of the TCR-Vgamma and -Vdelta repertoires tested in 2 of the individuals with expanded TCRgammadelta(+) T-cells was similar to that observed in control individuals. The results presented here provide evidence for an extensive T-cell activation during acute viral infection and establish the immunophenotype patterns associated with this condition.Blood Cells Molecules and Diseases 01/2003; 30(1):1-12. DOI:10.1016/S1079-9796(03)00014-7 · 2.33 Impact Factor
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ABSTRACT: Adhesion molecules, which play a major role in lymphocyte circulation, have not been well characterized in human immunodeficiency virus (HIV) infection. T-lymphocyte populations, including CD3, CD4, CD28, and adhesion molecules (L selectin, LFA-1, VLA-4, and ICAM-1) were measured by flow cytometry in a cross-sectional study of 100 HIV-infected and 49 HIV-seronegative adults. HIV-infected adults had lower numbers of CD3+ lymphocytes expressing L selectin (P < 0.0001) and VLA-4 (P < 0.01) and higher numbers of CD3+ lymphocytes expressing LFA-1bright (P < 0.002) than did HIV-negative adults. By CD4+-lymphocyte count category (>500, 200 to 500, or <200 cells/microl), HIV-infected adults with more advanced disease had lower percentages of CD3+ lymphocytes expressing L selectin and VLA-4 and higher percentages of CD3+ lymphocytes expressing LFA-1. The percentages of CD3+ CD28+ lymphocytes and of CD3+ L selectin+ lymphocytes were positively correlated (Spearman coefficient = 0.86; P < 0.0001), and the percentage of CD3+ CD28+ lymphocytes and the CD3+ LFA-1bright lymphocyte/CD3+ LFA-1dim lymphocyte ratio were negatively correlated (Spearman coefficient = -0.92; P < 0.00001). The results of this study suggest that HIV infection is associated with altered expression of adhesion molecules.Clinical and Diagnostic Laboratory Immunology 07/1998; 5(4):583-7. · 2.51 Impact Factor